Aliens or Not, We've Still Got A Lot To Learn From NASA's Kepler Mission

Maddie Stone 10/17/15 http://gizmodo.com

This week, the internet worked itself into a frenzy over the possibility that we’ve found an alien megastructure. But whether or not there’s a Dyson sphere buried in the Kepler data, the discovery of a strange, flickering star is very interesting.

Indeed, it points to an entirely new use for the spectral data on 150,000-odd stars that NASA’s Kepler mission spent four years acquiring: Finding and studying really weird astronomical phenomena.Aliens?!

If you missed the latest alien hysteria, here’s the gist: A thousand light years from Earth in the direction of the Cygnus constellation, a star known as KIC 846285 is behaving in an extraordinary manner. The star flashes and fades, light a lightbulb on a dimmer switch. On several occasions during our four years observing it, its light output dipped by over 20%.

It doesn’t look at all like the planetary transit events Kepler was built to detect — these will cause a star to dim periodically, by about 1% at most. As far as astronomers can tell, there’s nothing else like KIC 846285 in the Kepler database.

Dips in KIC 846285’s brightness over a 1500 day observational period. The bottom two panels are blown-up versions of the top one centered around day 800 and 1500. Image via Boyajian et al.

In a paper released on arXiv, a research team led by Tabby Boyajian proposes a number of natural explanations for the star’s light signature, including giant sunspots, epic clouds of cosmic dust, and a massive collision between two planet-sized objects. All of these scenarios are problematic for one reason or another. The most likely story is that a “family of exocomet fragments” were swept into orbit around KIC 8462582 when another star zipped close by.

Then there’s the unnatural explanation: Aliens. As astronomer Jason Wright explains in a forthcoming paper, KIC 8462852’s light pattern could be consistent with a “swarm of megastructures” built by an alien civilization to harness the star’s energy. Wright, Boyajian, and UC Berkeley SETI director Andrew Siemion are now proposing that we point a massive radio dish at the star, to hunt for the technobabble of an advanced society.

“I’m still stumped about what could be going on,” Wright told me in an email. “But something is clearly orbiting the star, and whatever they are, they are very large and have complex shapes.”

Whether or not the alien explanation holds water — and we should bear in mind that every time researchers have cried aliens in the past, they’ve been wrong — the fact that KIC 8462852 has piqued the interest of SETI is, in itself, interesting.

The Kepler mission was designed to stare unblinking at a fixed point in the sky, hunting for the tiny shadows of planets transiting across stars. And it’s done a beautiful job. To date, Kepler has uncovered over 4100 planetary candidates and 1000 confirmed exoplanets. Extrapolating from its small cosmic census, astronomers have reached an astounding conclusion.

“We have learned most stars have planets, that Earth sized planets are common, and a good fraction are in the habitable zone of their star,” lead Kepler investigator Bill Borucki said at an exoplanet conference I attended this past May. “And when you put the numbers together: 100 billion stars, 10 percent with Earth-sized planets, 10 percent stars like the sun, that’s a billion Earth-sized planets in the habitable zone of stars like the sun.”

The Kepler mission has literally revolutionized our view of the cosmos. Thirty years ago, we weren’t sure there were any Earth-like planets beyond our solar system, now, there could be a billion. The possibility of finding life beyond Earth is no longer a pipe dream.

But as recent the Dyson sphere hubbub shows, there’s more to Kepler’s wealth of data than planetary bean counting.

To wit, by deliberately seeking out weird spectral patterns within Kepler’s dataset, we might discover all sorts of interesting and bizarre astronomical phenomena. Wright imagines quite a few possibilities in a forthcoming paper, including gravitational interactions between planets, massive exomoons, asymmetrical stars, and yes, alien infrastructure. That last one is all that the popular press picked up on, but any of these discoveries would be fascinating.

KIC 8462852 also shows us how to go about finding the cosmically weird and unexpected: Human eyeballs. Our putative Dyson sphere was first noticed by Planet Hunters, a fleet of volunteer citizen scientists who have been trained to trawl through spectral data and pick out stars that look interesting. Because KIC 8462852’s flickering pattern is so irregular, it would have been tough for a computer algorithm to spot. But ordinary men and women on their lunch break could tell that this star was special, and now, SETI astronomers want to point radio telescopes at it.

It was first detected Oct. 19 by the University of Hawaii’s Pan-STARRS 1 telescope on Haleakala, Hawaii, as it scanned the sky to search for near-Earth objects for NASA. Calculations suggested it might be an interstellar interloper, and scientists announced Monday they have confirmed it came from outside our solar system.

Designated 1I/2017 U1 and nicknamed ‘Oumuamua — a Hawaiian word for messenger or scout — the object appears reddish in color and has an elongated shape.

“This thing is an oddball,” said Karen Meech from the University of Hawaii’s Institute for Astronomy, leader of an international team studying ‘Oumuamua. “What we found was a rapidly rotating object, at least the size of a football field, that changed in brightness quite dramatically. This change in brightness hints that ‘Oumuamua could be more than 10 times longer than it is wide — something which has never been seen in our own solar system.”

Measurements from an array of telescopes indicate the object is up to a quarter-mile (400 meters) long and spins once every 7.3 hours.

“We think this object — 2017 U1 — is very long … and very narrow, perhaps maybe 40 meters (130 feet) or so in the other dimension,” Chodas said. “That’s a very unusual shape. We don’t see that in our solar system. None of the asteroids in our solar system look like that, so it’s very puzzling how it could have obtained this shape.”

Data and findings were published in the Nov. 20 issue of the journal Nature.

Astronomers initially classified the discovery as a comet last month, but further observations showed it to be inert, with no signs of gas or dust around it, prompting scientists to consider it an asteroid.

‘Oumuamua’s dark reddish color is similar to the hue of many objects in the Kuiper Belt, a zone of dwarf planets and asteroid-like worlds orbiting the sun beyond Neptune. Its appearance suggests ‘Oumuamua is dense, made up of rock or metallic elements and lacks significant water or ice, scientists said.

“We also see that it’s very reddish in color, which indicates that it’s been possibly in space a long time and irradiated by not only the light from our sun, but other suns as well,” said Lindley Johnson, NASA’s planetary defense officer.

The European Southern Observatory’s Very Large Telescope in Chile aimed its aperture at the object to determine its, color, brightness and orbit, revealing it came from the approximate direction of the bright star Vega in the constellation Lyra. But Vega has moved in its path around the Milky Way galaxy since ‘Oumuamua passed near its current position some 300,000 years ago, so the asteroid’s origin is still unknown.

After following a steep trajectory toward the inner solar system, ‘Oumuamua is now on the outbound leg of its hyperbolic orbit traveling more than 85,000 mph (38 kilometers per second) relative to the sun. As of Monday, the object was about 124 million miles (200 million kilometers) from Earth, positioned between the orbits of Mars and Jupiter but tilted on a trajectory inclined around 20 degrees from the plane of the planets that orbit the sun.

It will pass Jupiter’s orbit in May 2018 and surpass Saturn’s distance from the sun in January 2019. ‘Oumuamua’s trajectory will next take it toward the constellation Pegasus.

‘Oumuamua made its closest approach to Earth on Oct. 14 — before its discovery — at a distance of about 15 million miles (24 million kilometers), or around 60 times the distance between the Earth and the moon.

“It’s fading very fast,” Johnson said. “It’s a relatively small object, so it’s very dim, but we are continuing to try to use NASA assets like the Hubble Space Telescope and Spitzer to take observations to determine more about its size and composition.”

“We are continuing to observe this unique object,” said Olivier Hainaut, an astronomer at the European Southern Observatory. “And we hope to more accurately pin down where it came from and where it is going next on its tour of the galaxy."